The ratio of black to green stamps that Hazel had was 5 : 3. The cost of each of the black stamps was $5 and the cost of each of the green stamps was $7. Hazel sold 40% of the black stamps and the total cost of the unsold stamps was $324. How many green stamps did she have left?
|
Black stamps |
Green stamps |
Before |
5 u |
3 u |
Change |
- 2 u |
|
After |
3 u |
3 u |
Number of black stamps sold
= 40% x 5 u
=
40100 x 5 u
= 2 u
|
Black stamps |
Green stamps |
Total |
Number |
3 u |
3 u |
|
Value |
$5 |
$7 |
|
Total value |
15 u |
21 u |
$324 |
Total cost of unsold stamps
= 15 u + 21 u
= 36 u
36 u = 324
1 u = 324 ÷ 36 = 9
Number of green stamps that Hazel had left
= 21 u
= 21 x 9
= 189
Answer(s): 189